The present invention relates to a controller and a control method for an internal combustion engine for determining a combustion state based on ion current.
To date, there has been known a controller for an internal combustion engine which determines a combustion state, such as preignition and knock, based on the ion current which flows into the discharge electrode of the spark plug. For example, in the technology disclosed in Japanese Patent Unexamined Application Publication No. 63-68774 (JP 63-68774 A), it is configured to determine that preignition with large intensity occurred in the case where generation of the ion current is detected before the ignition timing by the spark discharge of the spark plug.
In the technology disclosed in Japanese Patent Unexamined Application Publication No. 2009-57940 (JP 2009-57940 A), it is configured to determine the generation end timing of the ion current after the ignition timing, and determine the intensity of preignition based on the generation end timing.